This invention relates to synthetic blood vessel grafts. Although the invention also has other possible uses, the invention is particularly useful in conjunction with artificial heart valves.
The use of a composite valved graft is an established treatment for patients with aortic valve disease and ascending aortic aneurysms. It is preferred to have the graft part of the composite device supplied “preclotted” or pre-sealed. Having a pre-sealed graft not only eliminates the need for preclotting during surgery, it also tends to reduce the possibility of post-implantation bleeding, because the manufacturing process for pre-sealing can be carried out more consistently to reliably provide an adequate seal. The material used to seal the graft is hydrolysable, so that after implantation the sealant will be degraded and removed to allow the host tissue to grow into the graft to stabilize it and to cover the graft to form an ideal blood-contacting surface.
Because of the benefits of a preclotted graft, most mechanical valved grafts that are commercially available today are supplied with the graft pre-sealed. However, for a composite device that includes a valve made of tissue, the graft is not preclotted because the valve needs to be stored in a solution to prevent the tissue from dehydration. The material that would be used to preseal the graft portion of the device would react undesirably with the packaging solution. Therefore, for a Bentall procedure (replacement of aortic valve and adjacent section of the aorta) using a tissue valve, the surgeon has to either seal the graft portion of a composite device using the patient's blood, or construct a composite device using a tissue valve and a preclotted graft that are supplied separately. For the latter case, the available preclotted grafts are basically straight tubes that need to be carefully attached to the tissue valve to provide a structurally stable interface and adequately prevent blood leakage.
In view of the foregoing, it is an object of this invention to provide improved preclotted synthetic grafts, especially for use in conjunction with artificial heart valves, and most especially with tissue heart valves.